The invention pertains to the catch hook for a backrest adjustment armature in the seats of motor vehicles, which hook is mounted rotatably on a part of the armature to lock and release it, the armature part being designed to pivot forward together with a part of the seat and to rest, when in the locked position, against a stop on the base frame of the seat, force being exerted on the catch hook by a stored-energy device in the locking direction, the opening of the catch hook gripping behind the stop when in the locked position, where a tension latch, which also grips behind the stop when in the locked position, is arranged next to the catch hook, the latch itself being pivotably supported on the catch hook so that it can, as needed, be released from the locked position by an actuating element.
In the case of the catch hook described in DE 43 26 623 C2 for locking and releasing part of a backrest adjustment armature, which can pivot forward together with a part of the seat, a latch-like locking hook is again arranged next to the catch hook. This locking hook is connected to the catch hook by way of a driver, which gives the locking hook a certain freedom of movement. When the catch hook is in the locked position, the locking hook supports the catch hook and prevents it from sliding away from the stop attached to the seat part. A stored-energy device acting on the locking hook holds the locking hook against the catch hook, the locking hook being mounted with freedom of rotation on the catch hook. The locking hook also has a locking section, which, when the catch hook is in the locked position, is supported against an opposing support piece rigidly attached to the armature part. In addition, the axle journal of the catch hook is surrounded by a slot in the locking hook, which slot extends in the pivoting direction of the locking hook, the locking hook being put under tension with respect to the catch hook by an additional stored-energy device. In the normal position of the backrest, therefore, because one end of the locking hook is positively supported by the axle extending between the catch hook and the locking hook and the other end is supported on the opposing support piece of the armature part, the locking hook keeps the catch hook in a defined, ready-to-lock position against the stop of the seat part. At the same time, one end of the catch hook is supported on the axle journal of the armature part, while the other end is supported by its driver on the locking hook. Thus the catch hook is prevented from slipping at the start of a crash and remains in position. Nevertheless, this solution does not make it possible reliably to prevent the unused seats from making rattling noises.
Another previously known solution according to DE 38 28 223 C1 also discloses a catch hook with a tension latch next to it, but here both the catch hook and the tension latch are supported on the same bearing shaft attached to the armature part. Both the catch hook and the tension latch extend around a stop peg on the base frame of the seat. Whereas the catch hook serves primarily to retain the locked position, the role of the tension latch is to eliminate play by tensioning the armature part against the base frame of the seat. The catch hook and the tension latch can be moved by an actuating means in the form of, for example, a Bowden cable, in such a way that, upon the release of the armature part, first the catch hook and then the tension latch are pivoted away from the shaft. For this reason, both the catch hook and the tension latch have their own separate spring elements, by means of which the locked position of the catch hook and the locked position of the tension latch are restored after the backrest is tipped back again. The simultaneous arrangement of the catch hook and the tension latch on one and the same bearing shaft requires that the tensioning surface on the tension latch have a specific contour in the form of a wedge. Because the release movement of the tension latch trails after the release movement of the catch hook, the wedging effect which occurs means that, after the initial actuation of the release lever, extra force must then be exerted on the release lever to overcome the resistance. The ease with this system can operated therefore leaves something to be desired. In addition, the use of two restoring springs is also detrimental to the ease of operation, because, once the force of the first restoring spring has been overcome after a certain phase of the actuating movement, there is still the force of a second spring to be overcome. This makes it even more difficult to operate the system, in the sense that the amount of actuating force which must be expended is greater than it should be.
The task of the invention is not only to produce a rattle-free locking of the armature part to the base frame of the seat, but especially to facilitate the actuation of the catch hook and the tension latch for the purpose of increasing the ease of operation. This task is accomplished by the features cited in the characterizing clause of Claim 1. Although it is true that the actuating force originally introduced to release the catch must increase slightly over the course of the actuating distance as a result of the spring characteristic, it does not need to increase abruptly at a certain point over the course of the actuating distance, namely, at the point when the tension latch starts to carry along the catch hook, because the friction-producing effect caused by the contact between the tension latch and the stop has already been eliminated at the beginning of the release movement. The catch hook itself grips behind the stop on the base frame of the seat without a wedging effect, so that negligible force is required for the tension latch to drive the catch hook in the release direction. It is advantageous for the release force to be hinged to a release peg of the tension latch by way of an actuating element designed preferably as a Bowden cable.
In a first embodiment, support fingers, which act as support elements in addition to the axle journal which supports the tension latch on the catch hook, are formed by an opening in the tension latch and extend around the head of the shaft which supports the catch hook on the armature part. The opening surrounds the head of the shaft with play, so that the support fingers are a certain distance away from the circumference of the head of the shaft. As a result, the tension latch is able to move in advance of the catch hook when the release movement is initiated.
In another exemplary embodiment of the object of the invention, the release peg has a projection, which engages in a slot in the catch hook to serve as a support element in addition to the axle journal which supports the tension latch on the catch hook. This slot curves around the bearing journal, remaining equidistant from it, and is designed so that the tension latch can pivot freely over a short distance in the above-mentioned slot until the projection ultimately comes to rest against the upper edge of the slot, from which point on the tension latch carries the catch hook along with it.